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HANDBOOK 

OK 

CHEMICAL EXPERIMENTS 

FOR 

DENTAL STUDENTS 

f*f^O 

BY 

QeLANCEY WALTON WARD, Ph.B., Ph.D. 

PROFESSOR OF PH* SICS, CHEMISTRY AND METALLURGY IN THE COLLEGE OF 
DENTAL AND ORAL SURGERY OF NEW YORK 

\ 


FIFTH EDITION 





NEW YORK 

D. VAN NOSTRAND COMPANY 
8 Warren Street 
1921 








Copyright, 1921, By 
DeLANCEY WALTON WARD 


PRESS OF 

THE HEW ERA PRI NTING COMPANY 
LANCASTER. FA. 


g)Cl6611500 

APR -fc' 19 ?{ 


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/ 



FOREWORD 


In compiling this laboratory handbook the author has 
merely put into book form the general order of instruction 
and experiments used in his laboratory for a number of years. 
His aim has been to lead the student to do as much theoretical 
and practical work by himself as possible. All questions asked 
should be. answered, formulae inserted for all substances, and 
chemical equations worked out. 

It is the sincere wish of the author that this laboratory 
guide may help in the broadening and deepening of chemical 
knowledge and tend to promote the student’s appreciation of 
the importance of this subject in the study of dental medicine. 

De L. W. W. 

New York, December i, 1916. 

PREFACE TO THE FIFTH EDITION 

Exhaustion of the fourth edition has required a fifth for 
the laboratory work of this year. Revision and corrections 
have been made to bring the work up to date. 

De L. W. W. 


111 


New York, January, 1921. 









GENERAL CHEMISTRY 


THE BUNSEN BURNER 

This is a special form of burner for producing heat without 
light and smoke, by the more complete combustion of illu¬ 
minating gas. Examine burner and briefly describe it. 

The gas and air mix in the lower part of the tube and burn 
at the top. As the gas and the air are intimately mixed 
combustion takes place in all parts of the flame. Now close 
the valve at the bottom and notice the luminous flame. Pass 
a toothpick slowly through this flame. Then open the air 
valve and notice the difference in the color of the flame; also 
pass a toothpick slowly through the flame. Explain why the 
flame is almost colorless at first, and yellow afterwards (when 
the air valve is closed). What difference do you notice be¬ 
tween the two toothpicks ? Explain. There are various modi¬ 
fications of the Bunsen burner, but the principle is the same 
in all. 

BLOWPIPE 

The simple blowpipe is an instrument for producing a 
higher temperature than can be obtained with an ordinary 
flame, by introducing air (oxygen) into a flame and thus pro¬ 
ducing more complete combustion. 

It consists of a brass tube about 12 inches long. The 
smaller end is bent at a right angle, and terminates in a rein¬ 
forced opening. At the larger end a rubber mouthpiece is 

1 


































2 


usually employed to prevent contact of the brass with the lips, 
and also facilitate the operation of blowing. 

By placing the tip of the blowpipe at the edge of the flame, 
and blowing strongly a pointed flame, colorless at the outer 
part (oxidizing) yellowish within (reducing) is formed. Sub¬ 
stances heated at the first part tend to oxidize; oxides heated 
in the second part tend to be reduced. 

A yellowish flame rich in carbon or carbon gases is reducing. 

A bluish or colorless flame, due to complete combustion, 
is oxidizing. 

The proper and continuous use of the blowpipe (blowing 
a steady flame for two or three minutes) requires care and 
practice. The student must first learn to breathe regularly 
with the cheeks distended. In this way a continuous current 
of air can be supplied to the blowpipe. The cheek muscles 
must be exercised so as to keep up a continual tension on the 
air in the mouth. The lungs act like a force pump, and the 
mouth with the cheek muscles act like an air chamber. (See 
force pumps in physics.) 

THE WORKING OF GLASS TUBES, RODS, ETC. 

The working of glass tubes, etc., into various forms, pieces 
of apparatus, and so forth, is treated in many books on ele¬ 
mentary chemistry, also in special works on glass blowing. 
It is generally sufficient to be able to cut a piece of tubing, to 
round the ends by holding in a flame until soft, closing one end 
of the tube, and then blowing a bulb. Also bending and draw¬ 
ing out glass tubing and rods. 

In order to break off a piece of glass rod or tube, make a 
small scratch with a triangular file. Then grasp the tube or 
rod with both hands, the thumbs extending along the tube and 












3 


almost touching, and the scratch being on the opposite side. 
Now press gently with the thumbs and pull at the same time, 
when the tube will break at the mark. 

Before going further, the sharp edges of the tube or rod 
should be rounded, by holding the glass in the Bunsen flame, 
turning constantly, until the edges have melted and become 
round. 

If the above is continued, with a tube, the opening will 
become smaller and smaller and finally close. 

The closed tube can be used for making a bulb by heating 
about one-half an inch of the closed end of the tube and turn¬ 
ing constantly. When quite hot and soft, remove from the 
flame, apply the lips to the open end and blow slowly, turning 
the tube all the time. The soft glass will expand and form 
a bulb. 

Tubes may be drawn out into points by placing the “ wing 
top” on the burner (which gives a long, flat flame), and then 
holding the tube in the flame, and turning. When the tube is 
soft, pull slowly, turning at the same time,'and the soft tube 
will be drawn out to a smaller diameter. If the same method 
of heating a tube is used, when the tube is soft, it may be bent 
at any angle. 

Melting Point Tube. 

Take a piece of medium glass tubing f-inch bore and about 
6 inches long. Heat it in the flame and when soft draw it 
down to a tube about J inch. Cut off a piece of the reduced 
tube, about 3 inches long and seal one end by heating in the 
flame until closed. Then heat the tube carefully about 1 inch 
from the closed end and when soft reduce the caliber or make 
a constriction by pulling slightly. 






























4 


For further information consult Thomas Bolas, “ Glass 
Blowing and Glass Working.” 

WASH BOTTLE 

Examine the wash bottle and note each tube and its arrange¬ 
ment. When the wash bottle, filled with water, is inverted, the 
water will flow out of the tube with the larger opening. When 
the bottle is held in an upright position, and a current of air 
forced through the large tube by applying the lips and blowing, 
a fine jet of water will be forced out through the smaller tube. 

SOME IMPORTANT OPERATIONS 

Solution. —The diffusion of a solid, liquid, or a gas, through 
a liquid. It may be either mechanical, physical, or chemical. 

Sedimentation. —The separation of a mixture of a finely 
divided solid and a liquid, by letting it stand, the solid will fall 
to the bottom of the vessel by gravity, e. g., muddy water. 

Decantation. —The pouring off of the clear liquid after 
sedimentation. 

Filtration. —The separation of a mixture of a solid and a 
liquid (muddy water) by means of a porous substance or filter, 
upon which the mixture is usually poured. The liquid passes 
through (filtrate), but the solid (residue) is retained on the 
filter. Glass funnels with discs of paper made into cones and 
placed in the funnel are generally used in chemical operations. 

Precipitation. —The separating out of a substance, in the 
solid form, from a solution. It may be either physical or 
chemical. The former when the solution changes, as the sepa¬ 
ration of a salt from an aqueous solution by the addition of 




5 


alcohol. The latter, the formation of a new substance, in¬ 
soluble in the solvent, by changing the composition of the sub¬ 
stance in solution; as washing soda added to lime water, forms 
calcium carbonate, which is insoluble. 

Evaporation.—The separation of a liquid from a solid, 
either in suspension or solution, by converting the liquid into 
vapor and allowing it to escape. 

Distillation.—It is the same as evaporation except that the 
vapor is not allowed to escape, but is condensed by cooling, 
and collected. 

Sublimation.—The vaporization of a solid and its con¬ 
densation back to the solid state. 

Solubility.—(Unless the solvent is mentioned, water will be 
used.) 

The solubility of a substance may be determined by placing 
a small amount in a test tube, adding distilled water and shak¬ 
ing. If the substance disappears it is soluble. It may be only 
partially or slightly soluble and appear not to dissolve. In that 
case filter of! the liquid and evaporate the filtrate in a porcelain 
dish. If the substance was soluble there will be a residue left 
in the dish. 

GENERAL EXAMINATION OF SUBSTANCES 

As many students, in beginning the study of chemistry, and 
the examination of the different forms of matter, are at a loss 
as to the method of procedure, the scheme given below was 
introduced into my laboratory a number of years ago. 

This scheme should be followed for each substance and 
answers given on the blank pages. 

































. 











































• • 















6 


Solids. 

Color: 

Odor: 

Crystalline or amorphous, examine particles under micro¬ 
scope. Draw at least five different forms. 

Hardness: 

Scratched with the nail—soft. 

Scratched with a file—hard. 

Not scratched with a file—very hard. 

Melting-point: (see page 7). 

Specific gravity: 

Solubility: 

Magnetic: usually for metals only. 

Action of heat: Charring indicates a carbon compound. 

Combustible. 

DETERMINATION OF MELTING-POINT 

Prepare a melting-point tube. A small thin glass tube 
about 2 to 3 inches long, bore T V inch and closed at one end. 
About i inch from the closed end make a slight constriction by 
heating and drawing out. Fasten the tube to a thermometer, 
by means of a rubber band, so that the constriction is opposite 
the bulb. Bore a hole in a cork, insert the thermometer. Place 
a small piece of the substance whose melting-point is to be 
determined, in the open end of the small tube. It should be 
large enough to be retained at the constriction. The ther¬ 
mometer is immersed in melted paraffine contained in a test 
tube, so that the bulb is about 2 inches from the bottom of the 
tube. Heat the paraffine with a small flame and note the tem¬ 
perature at which the substance softens or slips down the 
construction which will be its melting-point. 



















































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Liquids. 

Color: 

Odor: 

Viscosity: 

Specific gravity: 

Boiling-point: 

Action on litmus paper: 

Blue becomes red = acid action. 

Red becomes blue = alkaline action. 

Neither affected = neutral. 

Both slightly = amphoteric. 

Combustible: 

Is it a solution or a simple liquid? Evaporate some and 
look for a residue. 

Gases. 

As gases tend to escape, unless confined, it is necessary to 
keep them in closed vessels, and also to prevent their mixing 
with the air. They also require special methods for collection, 
depending upon the nature of the gas. 

If heavier than air they may be collected by downward dis¬ 
placement, that is, by allowing them to flow into an upright 
bottle and displace the air (like a liquid). If lighter than air 
the bottle is inverted, and the gas, rising in the bottle, pushes 
out the air (upward displacement). Gases may also be col¬ 
lected over water (the method most commonly used), which 
is employed when the gas is only slightly soluble in water or 
not affected chemically by it. The bottle is filled with water, 
a glass plate placed on the mouth, and pressed down with the 
finger. This system is then inverted and the neck of the bottle 
carried below the surface of the water contained in a pan or 





8 


vessel called a pneumatic trough. The plate is then removed, 
the water remaining in the bottle. The gas is then allowed to 
enter at the mouth of the bottle, and rising displaces the water. 
When the bottle is full the glass plate is again placed on the 
mouth and the system removed from the trough. In some 
cases water cannot be used, and then a mercury trough is 
substituted. 

Color: 

Odor: 

Taste: 

Specific gravity. Whether it is lighter or heavier than air 
is usually sufficient. 

Solubility: 

Partly remove the cover, pour some water into the bottle 
(about I inch), replace the cover, and shake. The force re¬ 
quired to remove the cover, will give some idea of the quantity 
of gas dissolved, as the pressure will be proportional to the 
solubility of the gas. 

Action on litmus paper: Dry gases do not act upon dry 
litmus, the paper must be moistened with water before making 
the test. 

Is it combustible? 

Does it support combustion (like air) ? 

Is it indifferent, neither burns nor supports combustion ? 

THE STUDY OF CHEMICAL CHANGES 

(i) Analytic (separation). The separation of a substance 
into simpler forms of matter (compounds or elements). 

(a) Examine the substance given : 

Condition: crystalline or amorphous. 

Color: 




9 


Solubility: 

Heat some in a glass bulb, with tube bent in form of a V. 
Is a gas given off? Test with flame, test with spark on end 
of a toothpick. Does anything collect in the “ V ” part of the 
tube? If so, remove, and see if you can identify it. 

Is the change chemical? Give reasons. 

( b ) Examine limestone or chalk: 

Color: 

Solubility: 

Action on litmus paper: 

Heat some.in a small, hard glass tube, and test for gases. 
Examine the residue in the tube. Has it changed in appear¬ 
ance? Does it dissolve in water? Has it any action on 
litmus? Is the change chemical? Give reasons. 

(2) Synthetic (putting together). 

Examine iron filings. 

Examine flowers of sulphur. 

Prepare a mixture of the two in about equal parts, rub 
well together and answer the following: 

Are the iron and sulphur separate? Use microscope. 

Will a magnet separate the iron from the sulphur? 

Will carbon tetrachloride dissolve one and leave the other? 

Will hydrochloric acid dissolve one and leave the other? 
If a gas is given off, notice the odor. 

Heat some of the mixture in a small test tube. Does 
it glow? 

Then cool, remove the mass from the tube and examine: 

Microscope. 

Magnet. 

Carbon tetrachloride. 

Hydrochloric acid, and note if the gas given off has the 
same odor as before. 





























































































































































- 







































10 


Draw conclusions, as to a chemical change. 

Other chemical changes. —( a ) Examine a piece of zinc, 
then place it in a large test tube containing about 2 inches of 
hydrochloric acid dilute. 

Is a gas given off? It so, test. 

When all the zinc has disappeared filter the solution, if 
necessary, and evaporate the filtrate in a porcelain dish. 

Examine the residue, and give reasons for thinking a 
chemical change has taken place. 

Allow the dry residue to stand until the next period. What 
change do you observe ? 

( b ) Examine some crystals of copper sulphate. Heat 
some in a tube. What do you observe ? 

Dissolve some of the crystals in water, note color of the 
solution. 

Place a piece of clean iron into the solution, warm, allow to 
stand for a few minutes and answer the following: 

Has the solution changed in color ? 

Remove some of the red substance formed. Dry and rub 
with a knife blade. Can you identify it? 

Explain the changes. 

PREPARATION AND PROPERTIES OF OXYGEN 

Required: 

Hard glass tube, side-neck, and cork. 

Wash bottle for gas, with rubber stopper and tubes. 

Tin pan, glass bottles and flat covers, for collecting gas over 
water. Oxygen mixture (potassium chlorate two parts, and 
manganese dioxide one part). 

Sodium hydroxide solution for wash bottle. 

Set up apparatus as shown on the demonstrating table, heat 





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the oxygen mixture and when the gas appears at the delivery 
tube (spark on end of tooth pick will burst into flame), collect 
four bottles and make the following tests: 

(1) With one bottle determine: 

Color: 

Odor: 

Solubility: 

Action on litmus: 

(2) In another bottle burn some wood, add water, shake 
and test with litmus paper. 

(3) Burn sulphur in another and test as in (2). 

(4) Burn magnesium ribbon in another and test as in (2). 

What are your conclusions in regard to combustion in 

oxygen ? 

FLAME TESTS 

Some substances, when heated in the clear Bunsen flame, 
will impart a color which is characteristic for that substance 
and serves for its identification. These tests are made by 
heating the substance on a clean platinum wire, as follows: 

Clean the platinum wire by dipping it into concentrated 
hydrochloric acid and holding it in the flame, until all color 
has disappeared. Then, without touching the wire, dip it into 
the substance to be tested and hold in the flame again; note 
color imparted. If to the substance (being a solid) a small 
amount of pure hydrochloric acid concentrated, is added, better 
results will be obtained, as the chlorides formed are very 
volatile. 

Report flame color of the following salts, cleaning the wire 
before each test: 

Potassium chloride. 

Calcium chloride. 









12 


Lithium chloride. 

Barium chloride. 

Strontium chloride. 

Sodium chloride. 

Instead of platinum wires thin charcoal sticks may be used. 
Heat the stick in the flame to be sure that it is free from im¬ 
purities, then dip it into the solution or the solid substance, hold 
it in the flame and note the color. 

HYDROGEN 

Set up an apparatus as shown on demonstrating table; the 
large test tube, supported in the iron clamp, with rubber stopper 
and delivery tube. Fill the large test tube about one-third full 
with sulphuric acid dilute and add a few pieces of zinc. As 
soon as there is a brisk evolution of the gas* place a small test 
tube over the delivery tube. In a few minutes remove the 
small test tube, keeping the mouth downward, and test the gas 
with flame; when the gas burns quietly or without explosion 
fill several test tubes in the same manner and make the 
usual tests. 

The above apparatus can be used for other light gases. 

Color: 

Odor. (May be an odor from impure zinc.) 

Action on litmus paper. 

Does the gas support combustion? 

Collect some in a dry tube, and ignite what is formed. 

Give reasons for your answers. 

Hydrogen can also be prepared (in a pure state) by the 
action of sodium on water 

* If the gas is evolved very slowly, add a few drops of a solution 
of copper sulphate to the mixture; can you explain how this accelerates 
the reaction? 










13 


Fill a test tube with water, place thumb over end and invert 
in a basin of water. Take a small piece of sodium, in the 
iron forces, bring it quickly below the mouth of the test tube 
and release. What do you observe ? When the action is over 
test the gas. Also test the water in the basin with red litmus 
paper. Explain the reaction. 

Hydrogen is the essential element of all acids, but hydrogen 
ions only give an acid action; the element is neutral. 

SOME ACID TESTS 

The so-called acid tests are of considerable importance, and 
have to be made from time to time even in the early study of 
chemistry. Two tests with method will therefore be given. 

These are made for the part or radicle associated with the 
hydrogen (anions). 

Test for chlorine ions. 

Make the solution slightly acid with dilute nitric acid, then 
add a few drops of silver nitrate solution. A white, curdy pre¬ 
cipitate is formed, which blackens in the light, and is soluble in 
ammonium hydroxide. 

Test for sulphuric ions. 

Make a solution slightly acid with dilute hydrochloric acid 
and add a few drops of barium chloride solution, a heavy white 
precipitate of barium sulphate is formed. Other acid tests 
will be given later. 


HYDROGEN DIOXIDE 

Pour about 20 c.c. or dilute sulphuric acid into a small 
breaker, place on a wire gauze on the ring stand. Add, in 
small portions at a time, 10 grams of powdered barium dioxide 
and stir well. Heat the mixture carefully for a few minutes, 


























































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14 


but do not boil. Then add barium carbonate slowly with 
stirring until there is no further effervescence, showing that 
excess of sulphuric acid has been neutralized. Heat for a 
short time, filter off the barium sulphate, cool the filtrate and 
test with potassium iodide starch mixture. A blue coloring 
of the starch indicates hydrogen peroxide. 

Make the following tests: 

(1) Add some dilute chromic acid solution to hydrogen 
peroxide. Note change of color due to the formation of per- 
chromic acid. 

(2) Add some hydrogen peroxide to a dilute solution of 
potassium permanganate. Observe change and explain the 
reaction. 

(3) Hydrogen peroxide added to a solution of titanic 
sulphate Ti(S 0 4 ) 2 gives a yellow color due to the formation 
of pertitanic acid. 

EXAMINATION OF THE HALOGENS 

Fluorine.—This element has been prepared only with great 
difficulty, so will not be studied in the laboratory. 

Hydrofluoric Acid.—(1) Place some calcium fluoride in a 
leaden dish and add concentrated sulphuric acid sufficient to 
cover the powder. Place on a ring stand and heat with a small 
flame. Cover the convex side of a watch glass with paraffine, 
by warming the glass and rubbing a piece of parafflqe over the 
surface. When cool make some marks with a hard instru¬ 
ment on the paraffine so as to expose the glass. Place the 
glass, convex side down, on the lead dish and let it remain for 
half an hour. Then take off the watch glass, and remove the 
paraffine by warming and rubbing with a towel. Explain the 
phenomenon and write the equations. 











15 


(2) Clean a microscopic slide and make some tracings with 
hydrofluoric acid solution. Allow to stand for ten minutes, 
wash off with water and explain the phenomenon. 

(3) Clean a piece of glazed porcelain, a portion of the out¬ 
side of a porcelain dish will do; then place a drop or two of a 
solution of hydrofluoric acid on the dish, allow to remain thus 
for a few minutes. Wipe off the acid with a wet cloth, and 
note the roughness of the surface of the dish. If the result is 
not good the first time repeat the application of the acid to the 
same two or three times. Explain. 

Chlorine.—Place about half an inch of manganese dioxide 
in a large test tube, add about 10 c.c. of hydrochloric acid cone., 
heat carefully, and collect the gas by downward displacement. 

Color: 

Odor: 

Light or heavy: Can the gas be poured from one tube to 
another ? 

Solubility: allow the gas to come in contact with some 
water in another tube, and shake well. 

Action on litmus paper: 

Does it burn? 

Does it support combustion ? 

Try action on a piece of dyed cotton cloth: the cloth must 
be wet. Why? 

Introduce some bleaching' powder into a large test tube, add 
some sulphuric acid dilute; warm and try the action on litmus 
paper, first dry, then wet. Explain. 

Hydrochloric Acid Gas.—Place some sodium chloride in a 
large test tube, fitted with rubber stopper and doubly bent tube. 
Add sufficient concentrated sulphuric acid to cover the salt 















16 


completely, insert the stopper and heat carefully. Write the 
equation. 

Test with litmus paper, first dry, then wet. 

Fill several tubes and test gas as usual. 

Make a solution and test: 

Hydrogen ions. 

Chlorine ions. 

Aqua Regia.—A mixture of hydrochloric and nitric acids, 
which gives off chlorine. Write the equation, and explain. 

Add a few pieces of gold to a mixture of dilute hydro¬ 
chloric acid (3 parts) and dilute nitric acid (1 part), heat until 
gold is dissolved. Write the equation. 

Bromine.—Prepare a mixture of potassium bromide and 
manganese dioxide. 

Place in a large test tube same apparatus as for hydro¬ 
chloric acid and add some dilute sulphuric acid. 

What is set free? 

Color: 

Odor: 

Light of heavy? 

Is it soluble in water? In carbon tetrachloride? 

Add a few drops of dilute hydrochloric acid to a bromide 
solution and about 1 c.c. of carbon tetrachloride, which will fall 
to the bottom of the tube. Then add some chlorine water, 
shake, let stand and observe that the globule at the bottom of 
the tube is colored yellow or yellow-red, due to the presence of 
bromine. 

Add more chlorine water and see if the color can be 
bleached. 

Iodine.—Condition: 

Form: 





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Color: 

Odor: 

Solubility in: 

Water. 

Alcohol. 

Carbon tetrachloride. 

Note colors of the last two solutions. Can you explain the 
difference ? 

The tincture contains potassium iodide. Why ? 

Heat some iodine in a small test tube held almost hori¬ 
zontal and observe. 

Does it melt? 

Does it vaporize without melting (sublime) ? 

What is the color of the vapor? 

Condense same and examine particles under microscope. 

Test for Iodine. —Add one drop of Lugol’s solution* to 
some dilute starch paste in a test tube, shake and note color. 
Heat the tube and note what happens. 

Allow to cool and note again. 

Can you explain the changes? 

Test for Iodine Ions. —This test is made in the same manner 
as that for bromine (see page 17). 

Add more chlorine water and see if the color disappears. 
Iodine and bromine ions precipitate silver nitrate solution 
as well as chlorine ions giving silver iodide and bromide, re¬ 
spectively. All are affected by light. (Photography.) 

NITROGEN 

Preparation: by burning out the oxygen from air. 

Tall, graduated bell jar, open at the top; deflagrating spoon 
*A solution of potassium iodide and iodine in water. 












































18 


for burning phosphorus and rubber stopper; also a deep, wide 
glass jar or pneumatic trough, containing some water. 

Place the bell jar partly in the water, read the volume of 
air, and, without changing the level of the water, introduce 
the deflagrating spoon with some burning phosphorus, also 
inserting the rubber stopper. Lower the jar somewhat to 
prevent the escape of any air and when the combustion ceases 
allow the gas to cool and the white vapor to be absorbed by the 
water. Then raise or lower the jar until the level of the water 
is the same within and without and read the volume of the 
gas. Why should the water levels be made the same? 

Determine the per cent of this gas in air? 

Does it burn? 

Does it support combustion? 

Has it any effect on lime water? 

It is not pure nitrogen, but contains about i per cent of 
argon and small quantities of rare gases. 

Ammonia 

Heat a mixture of an ammonium salt, with calcium 
hydroxide using an apparatus like that for hydrogen, and 
examine the gas evolved. 

Color: 

Odor: (Smell carefully.) 

Action on wet, red litmus paper: 

Solubility. 

Does it burn? 

Does it support combustion? 

Moisten a glass rod with concentrated hydrochloric acid, 
and hold in the gas; what do you observe? Explain. 

Pass some of the gas into water and test the solution. 
What is formed? and why does the water become alkaline? 



t. .J> 









19 


Test for ammonium, either in a salt or in solution (ammo¬ 
nium ions). Place some of the substance in a test tube add 
about one inch of caustic soda solution, heat and test gas with 
wet, red litmus paper. The paper will become blue if am¬ 
monium is present. 

Nessler’s Test. —Nessler’s solution* added to a colorless 
solution of an ammonium compound will give a yellow color 
or preciptate, depending upon the amount present. This is a 
very delicate test so use a very weak solution, (i: 100,000.) 

Nitric Oxide 

Prepare a gas generator consisting of a wide-mouthed 
bottle, rubber stopper with two holes, funnel and delivery tube; 
also pneumatic trough. 

Place some copper in the generator with sufficient water to 
cover it. Then pour concentrated nitric acid through the 
funnel tube until there is a brisk evolution of gas. Collect 
three bottles; the gas should be colorless. The orange fumes 
appearing in the generator are nitrogen dioxide and are dis¬ 
solved by the water. 

Open one bottle of gas and notice change of color. Explain. 

Try the combustion of sulphur. 

Try the combustion of phosphorus. Explain the difference. 

Nitric Acid 

Set up a glass-stoppered retort and receiver. The retort 
supported on a wire gauze and held by a clamp. All the glass 
apparatus should be dry. 

Introduce some sodium nitrate into the retort, and add 

*A solution of mercuric iodide in potassium iodide, and made 
alkaline with caustic soda. 





















































































































20 


enough concentrated sulphuric acid to cover it. Heat care¬ 
fully and distil off the nitric acid. Make the following tests: 

Color: 

Odor: , 

Solubility: 

Taste. Place one drop in a test tube half full of water, 
mix and taste. 

Action on litmus paper. 

Action on copper: write the equation. 

Action on tin: and state if it differs from that of copper. 

Action on wool: Place a small mass of worsted in the neck 
of a test tube'containing about half an inch of concentrated 
nitric acid. Heat, record phenomena. 

Action on turpentine, an inflammable substance. Place 
some nitric acid in a test tube, standing in the rack, then add 
some turpentine, a few drops at a time, by means of a long 
glass tube. (Do not stand near the test tube.) Note phe¬ 
nomena and explain. 

Test for nitric ions. 

Add a crystal of ferrous sulphate to the solution, then allow 
concentrated sulphuric acid to flow down the side of the tube 
slowly and collect in the bottom, where the two liquids meet, 
a brown ring will appear. 

Preparation and Properties of Nitrous Oxide 

Set up an apparatus, as shown, on the demonstrating table. 
Hard glass tube, with side neck and a cork. The tube sup¬ 
ported in a clamp, and the side neck joined to two wash bottles. 
The first contains a solution of ferrous sulphate; the second a 
solution of caustic soda. The delivery tube extends into warm 
water in the pneumatic trough. Place some ammonium nitrate 













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21 


in the hard glass tube. Insert the cork into the neck and heat 
carefully. When the salt is melted and appears to begin to 
boil, test the gas evolved at the delivery tube with a spark on 
the end of a toothpick. When the spark is in flame, collect six 
bottles of the gas. Remove the cork from the hard glass tube 
before taking away the flame, to prevent back suction of the 
ferrous sulphate solution, causing an explosion. 

Examine the gas: 

Color: 

Odor: 

Taste: 

Solubility. 

Action on litmus paper. 

Does it burn ? 

Bum wood and test. 

Burn sulphur and test. 

Burn magnesium and test. 

Do you think it would support life ? 

Test the ammonium nitrate for: 

(a) Ammonium group. 

( b ) Nitrate group. 

Difference between nitrous oxide and air (oxygen). 

Fill two wide-mouth bottles with nitric oxide, cover care¬ 
fully, so as to exclude all air (oxygen). Then fill a bottle 
(with the same sized neck) with nitrous oxide, being also care¬ 
ful to exclude air; also fill one bottle with air (oxygen). Ar¬ 
range the bottles containing the air and nitrous oxide on the 
table, mouths upward. Bring the two bottles containing the 
nitric oxide, mouths downward, over the others; rapidly 
remove the covers and bring the bottles set mouth to mouth, 
note difference between the two systems and explain. 

















22 


EXAMINATION OF CARBON 

Heat a piece of wood charcoal on the wire gauze with the 
Bunsen flame, and explain the change. 

Carbon is always obtained when organic matter (plant or 
animal), is heated in closed vessels or out of contact with air. 
Gaseous and liquid products are also formed. 

Destructive distillation. Heat a piece of wood in a large 
test tube, held almost horizontal. Explain changes and iden¬ 
tify products formed as far as possible. 

Carbon Dioxide 

Prepare a gas generator, consisting of a wide-mouth bottle, 
rubber stopper with two holes, funnel tube, delivery tube, pneu¬ 
matic trough and bottles for collecting the gas. 

Introduce some limestone into the generator, with some 
water to cover it. Then add enough hydrochloric acid to start 
a brisk effervescence. Test for the gas at the delivery tube 
with a spark on the end of a toothpick. When the spark is 
extinguished collect the gas. 

Then make the following tests: 

(1) Collect a bottle of gas by downward displacement 
(dry gas), and test with blue litmus paper, first dry then wet; 
note difference and explain. 

(2) Burn some 'magnesium ribbon in a bottle of the gas; 
can you explain the combustion ? 

(3) Add some lime water to a bottle of the gas, shake and 
explain. 

(4) Pass the gas into lime water, note action as in (3), con¬ 
tinue to pass in the gas until clear. Can you explain the 
change ? 

Divide the solution from (4) into two parts: 










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23 


(5) To one portion add some tincture of soap solution, 
shake and explain. 

(6) Boil the other portion and explain. 

(7) Filter the mixture obtained from (6), add soap solu¬ 
tion, shake and explain the difference between (5) and (7). 

(8) Breathe into lime water contained in a large test tube. 
What do you observe? Explain. 

Carbon dioxide is formed in all cases where carbon is 
oxidized by excess of oxygen. 

Carbon Monoxide* 

This gas is formed by the reduction of carbon dioxide, also 
by the decomposition of certain carbon compounds. 

Heat oxalic acid with concentrated sulphuric acid in the 
tube of an apparatus similar to that for hydrogen and pass the 
gases evolved through a solution of caustic soda to remove the 
carbon dioxide, also formed. Collect the gas over water. 

Test its properties as usual. 

Burn some in a bottle with the mouth downward, and test 
with lime water. Explain. 

Methane (Marsh Gas) 

Heat a mixture of soda-lime and dry sodium acetate in a 
large test tube, etc., collect the gas over water. 

Color. 

Odor. 

Light or heavy? 

Solubility. 

Action on litmus. 

Does it burn ? 

* This gas is very poisonous, so do not inhale any. 

















24 


Does it support combustion? 

Burn some and test products with litmus paper, with lime 
water. 


Acetylene* 

Pour about io c.c. of water into the large test tube of the 
hydrogen generator and add two or three small pieces of cal¬ 
cium carbide; notice the effervescence. Collect the gas over 
water. 

Color. 

Odor. 

Light or heavy? 

Action on litmus. 

Does it support combustion ? 

Burn gas and notice the character of the flame, test the 
products of combustion with lime water. 


Cyanogenf 

Place some mercuric cyanide in a test tube, fitted with a 
cork and a jet tube. Heat in the Bunsen flame, and note the 
burning gas. 

Explain the color of the flame and products of combustion. 


SULPHUR 

Color. 

Odor. 

Taste. 

Solubility, in water, carbon disulphide, ether. 

Prepare a solution of sulphur in carbon tetrachloride, filter 


* This gas is explosive and also poisonous, 
t This gas is exceedingly poisonous, so do not .inhale any. 















25 


and allow some of the filtrate to fall on a microscopic slide; 
when the solvent has evaporated examine the crystals under 
the microscope, draw some and try and determine their crystal¬ 
line form. 

Sulphur Dioxide 

Place some sodium sulphite in a large test tube, fitted with 
rubber stopper and bent delivery tube, add some hydrochloric 
acid and collect the gas by downward displacement. 

Color. 

Odor. 

Action on litmus, first dry, then wet. 

Solubility. 

Does it burn ? 

Try action on some weak fuchsin solution and explain; 
does any change take place after standing several hours ? 
Explain. 

Sulphuric Acid 

Bring two bottles together mouth to mouth; the one above 
containing sulphur dioxide, the one below nitrogen dioxide, 
allow them to stand and observe changes. Later, add a small 
amount of water to each, shake, mix and test for: (a) hydro¬ 
gen ions, (b). sulphuric ions with barium chloride solution a 
white precipitate of BaS0 4 is formed. Write all the 
equations. 

Sulphuric acid may be prepared in a small way for tests, 
by the following method:* 

Heat a mixture of sulphur with about twice its bulk of 
potassium chlorate in a small test tube, use a test tube holder. 

* This laboratory method of preparing sulphuric acid was first sug¬ 
gested to me a number of years ago by Prof. H. T. Vulte, Teachers 
College, Columbia University. 














26 


Explain the phenomenon (deflagration). Let the tube cool, 
add some distilled water, shake and let stand until liquid is 
clear. Pour off the clear liquid and test. 

(1) For hydrogen ions. 

(2) For sulphuric ions. 

Write all the equations. 

Examine some of the sulphuric acid in the bottle on the 
deck for: 

Color. 

Odor. 

Viscosity (limpid or oily). 

Pour some into cold water very carefully. Note effect 
and explain.* 

Try the action on: 

(1) Zinc; first dilute, then concentrated. 

(2) Copper; first dilute, then concentrated, with heat. 

(3) Sugar; place some sugar in a large test tube, supported 
in a holder, then add some concentrated sulphuric acid 
carefully. 

(4) Wool; make test the same as (3). Explain each 
action. 

Normal Solutions. 

Explain what is meant by normal sulphuric acid, normal 
hydrochloric acid and normal sodium hydroxide solutions. 

Prepare 50 c.c. of normal sulphuric acid, starting with 50 
per cent sulphuric acid. Use a burette for measuring the acid 
and the distilled water. Determination of the strength of an 
unknown sodium hydroxide solution. Place 20 c.o of the 
solution in a small beaker, add a few drops of litmus solution 

* When mixing the acid with water the above order should be used 
to avoid serious accidents, which are not uncommon. 






































































27 


and note the blue color due to the alkali or hydroxyl ions. 
Fill a burette to the o mark with the N-sulphuric acid and 
support it in the iron clamp on the ring stand. Allow the acid 
to fall drop by drop into the alkali, stirring the mixture with 
a glass rod, until the blue color becomes pink or just red, show¬ 
ing that the alkali has been neutralized. Read off the number 
of c.c. of acid used and calculate the strength of the sodium 
hydroxide, or the amount of the sodium hydroxide in the 
50 c.c. of solution. 

Carbon Disulphide 

Condition: 

Color: 

Odor: 

Light or heavy? 

Solubility: 

Is it inflammable? 

Solvent action on: 

(1) Sulphur. 

(2) Rubber. 

How would you distinguish this compound from: 

(o) Carbon tetrachloride? ( b ) Chloroform? 

Hydrogen Sulphide 

Arrange a large test tube with rubber stopper and bent 
glass tube as in other experiments for the preparation of gases. 
Introduce some pieces of ferrous sulphide into the tube and 
add enough dilute hydrochloric acid to cover them. Observe 
the effervescence. Examine the gas: 

Color. 

Odor. 

Solubility 















28 


Action on litmus paper. 

Does it burn? If so, what is found? 

Does it support combustion? 

Test with lead paper.* 

Reactions of Some Metals (Cations) with Hydrogen Sulphide 

Treat solutions of the following metals with hydrogen 
sulphide, note the effect on each, and write the equation. 

Zinc.—Precipitated by hydrogen sulphide in alkaline or 
acetic acid solution as zinc sulphide; white precipitate soluble 
in dilute mineral acids. 

Lead.—Precipitated by hydrogen sulphide in acid solution 
as lead sulphide, black preciptate, insoluble in dilute acids, is 
converted into lead sulphate (white), by the action of hydrogen 
peroxide. 

Copper.—Precipitated by hydrogen sulphide in acid solution 
as copper sulphide, blue black precipitate soluble in nitric acid 
(distinction from mercuric sulphide). 

Cadmium.—Precipitated by hydrogen sulphide in acid solu¬ 
tion as cadmium sulphide, bright yellow precipitate soluble in 
nitric acid, insoluble in ammonium sulphide (distinction from 
arsenic sesquisulphide). 

Bismuth.—Precipitated by hydrogen sulphide in acid solu¬ 
tion as bismuth sulphide, black precipitate, soluble in nitric 
acid (distinction from mercuric sulphide). 

Tin.—(Stannous or stannic.) 

Both precipitated by hydrogen sulphide in acid solution, 

♦Made by moistening a piece of filter paper with lead acetate 
solution. 










29 


stannous sulphide, brown precipitate; stannic sulphide, yellow 
precipitate. Both soluble in ammonium sulphide. 

Mercury.—Mercurous: Precipitated by hydrogen sulphide 
as mercurous sulphide, mixed with mercury, black precipitate, 
insoluble in ammonium sulphide; soluble in aqua regia. 

Mercuric: Precipitated by hydrogen sulphide, in acid solu¬ 
tion as mercuric sulphide, black precipitate, insoluble in am¬ 
monium sulphide, and dilute nitric acid; soluble in aqua regia. 

Silver.—Precipitated by hydrogen sulphide as silver sul¬ 
phide, black precipitate, soluble in hot nitric acid. 

Gold.—Precipitated by hydrogen sulphide in acid solution 
as gold sulphide, insoluble in acids, soluble in aqua regia, and 
in ammonium sulphide. 

Platinum.—Precipitated by hydrogen sulphide in acid solu¬ 
tion as PtS 2 , soluble in^ammonium sulphide and aqua regia, 
insoluble in acids. 

BORON 

Boric Acid. 

Condition: 

Color: 

Odor: 

Taste: 

Solubility: 

Action on litmus paper: 

Make flame test. 

Heat some in the loop of the platinum wire until all action 
ceases. Note the clear bead. What is formed? 

Borax. 


Color: 












30 


Odor: 

Taste: 

Solubility: 

Action on litmus paper: 

Make flame test. 

Heat with H 2 S0 4 cone, add alcohol, ignite and note color 
of flame. 

Borax gives a yellow flame due to the sodium present. 

Bead tests. 

Make a head in the loop on the end of the platinum wire, 
by heating wire and dipping it into the borax and heating 
again. The bead should be clear and colorless. 

Heat bead and dip it into some cupic oxide; heat again and 
note color. What is formed? 

Make separate bead tests for the following in the same 
way and report, color of each, while hot as well as cold. 

Cobalt oxide. 

Nickel oxide. 

Ferric oxide. 

Magnanese oxide. 

Chromium sesquioxide. 

Borax is called an acid flux. Why ? 


Silica. 


SILICON 


Examine silica (clean white sand will do). 
Color: 

Odor: 

Taste: 

Solubility: 

Fusibility: 













31 


Prepare a microcosmic salt (sodium ammonium hydrogen 
orthophosphate) bead on the platinum wire, when clear, dip 
bead into silica while hot and heat again; notice the skeleton¬ 
like mass floating in the bead while hot which disappears on 
cooling. 

Silicic Acid. 

Dissolve some sodium silicate in water, filtering if neces¬ 
sary ; observe the character of the solution. 

Test with litmus paper. 

Make some of the solution acid with hydrochloric, do you 
observe any change? 

Is it still a solution? Can it be filtered? 

Dialize some and examine the dialysate. 

Evaporate some of the dialized liquid and heat the residue. 
Is the residue soluble in water? Make a microscopic salt 
bead and examine while hot. 

» 

PHOSPHORUS 

Compare the properties of red and yellow* phosphorus. 
Condition: 

Color: 

Odor: 

Solubility in carbon disulphide. 

Combustibility with slight heat? 

What is formed when exposed to the air? 

What is formed when they burn? 

Phosphorus Pentoxide. 

Place a piece of dry phosphorus in a deflagrating spoon, 

* Keep yellow phosphorus under water until wanted. Do not 
handle it. 


















32 


heat until it takes fire and allow it to burn in a bottle of 
dry air. 

Examine the product. 

Condition. 

Color. ‘ 

Action on water and solubility. 

Ortho Phosphoric Acid. 

Use the above solution for the following tests: 

Hydrogen ions. 

Ortho phosphoric ions with: 

(a) Ammonium molybdate solution. 

( b ) Magnesia mixture.* 

(c) Silver nitrate. 

Examine Meta or Glacial Phosphoric Acid. 

Condition: 

• Color: 

Odor: 

Solubility: 

Action on litmus. 

Taste. (Use a dilute solution.) 

Use a fresh solution for tests. 

Compare Solutions of Each Acid. 

Meta. Orth. 

Action on albumen solution. 

Action on silver nitrate solution. 

Action on barium chloride solution. 

Prepare a dental cement by mixing some phosphoric acid 
solution with zinc oxide. What is formed? 

* A solution of magnesium sulphate made alkaline with ammonium 
hydroxide and ammonium chloride added until the solution is clear. 






33 


Phosphorus Acid. 

Allow some pieces of yellow phosphorus to stand in a 
bottle with a small quantity of water. (See the ozone experi¬ 
ment.) Later add a few c.c. of water, shake and pour off 
the solution from the residual phosphorus. Make the fol¬ 
lowing tests: 

(a) Hydrogen ions. 

( b) With silver nitrate. 

Phosphorus acid may also be made by the action of water 
on phosphorus trichloride. Write the equation. 

Phosphorus Tri-iodide. 

Dissolve about i.o gram of yellow phosphorus in 25 c.c. 
of carbon tetrachloride contained in a 200 c.c. flask. Add 12 
grams of iodine in small portions at a time, shaking after 
addition. When all the iodine has been added and passed into 
combination, connect the flask with a condenser and distil off 
the carbon tetrachloride, on a water bath. Examine the 
residue. 

Condition. 

Color. 

Odor. 

Melting-point. 

Action of water, write the equation. 

EXAMINATION OF ARSENIC* 

Condition: 

Crystalline form: 

Color: 

* Great care must be taken not to breathe any fumes evolved in 
these experiments with arsenic, as they are very poisonous. 



































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84 


Is it lustrous ? 

Is it soft or brittle ? 

Heat some, mixed with charcoal to prevent oxidation, in a 
large test tube, held in a horizontal position. 

Examine crystals. 

Heat some, as above, mixed with potassium nitrate, to 
oxidize it. 

Does it sublime ? Examine the crystals. 

What is their color? 

Remove some of the crystals, dissolve in water and test with 
litmus paper. What is formed? 

Arsenious Oxide. 

Condition: 

Color: 

Odor: 

Solubility: 

Heat a small piece and note odor; use care. 

Test the solution with litmus paper. 

Make solution acid with hydrochloric acid dilute and pass 
in hydrogen sulphide gas. Write the equation. 

Place a piece of clear copper into some of the solution, 
allow to stand for some time, note effect and explain. (Reinsch 
test.) Remove the copper, wash, dry, and heat carefully with 
a small flame; note fumes and their odor. 

Arsenic Acid. 

Condition: 

Color: 

Odor: 

Solubility: 












35 


Make a solution slightly acid with hydrochloric acid dilute, 
and divide into four parts: 

(1) Pass in hydrogen sulphide gas and note the effect. 

(2) Add a few crystals of sodium sulphite, boil and pass in 
hydrogen sulphide gas. 

Compare (1) and (2) and explain. 

(3) Add ammonium molybdate solution, first cold, then 
warm mixture and note result( dif. H 3 P 0 4 ). 

(4) Add magnesium mixture ;* note ppt. of NH 4 MgAs 0 1 . 

MARSH TEST FOR ARSENIC AND DISTINCTIONS 
BETWEEN ARSENIC AND ANTIMONY 

Hydrogen Arsenide. 

Prepare a hydrogen generator consisting of a flask (500 
c.c.), rubber stopper with two holes, a funnel tube and a jet 
for burning the gas. Place ^ome pure zinc in the flask and 
add enough distilled water to cover it. Then pour in through 
the funnel tube some pure concentrated sulphuric acid until 
there is a brisk evolution of gas. Wait a few moments to 
allow the hydrogen to drive all the air out (otherwise, when 
a flame is applied there will be an explosion), then light the 
gas. Observe. The color of the flame: It should be dark blue 
or colorless, not grayish blue (indicating arsenic). 

Place a piece of cold porcelain in the flame. No dark spots 
should appear on the porcelain. Now add a few drops of a 
solution of arsenious acid and observe change in the color of 
the flame. 

Place the porcelain in the flame, as before. Brownish 
black spots with a metallic luster indicate arsenic. Test the 


^7 


* See foot-note, page 35. 






























































































































* 








































































36 


solubility of the spots in : ( a ) chlorine water, should be soluble; 
( b ) in hydrochloric acid, should be insoluble. 

Hydrogen Antimonide. 

Use a similar apparatus and a solution of antimony 
chloride. 

Observe the color of the flame, which should be grayish. 
The spots on the porcelain should be somewhat sooty in ap¬ 
pearance, blacker and lusterless. 

Test the solubility of the spots in (a) chlorine water, 
should be insoluble; ( b ) hydrochloric acid, should be soluble. 

Other Distinctive Tests. 

A solution of arsenious acid or arsenite, made slightly 
acid with hydrochloric acid, treated with hydrogen sulphide, 
gives a yellow flocculent precipitate of arsenic sesquisulphide. 

With the same reagent a solution of antimony gives an 
orange flocculent precipitate of antimony sesquisulphide. 


QUALITATIVE ANALYSIS 

Tests and separations for the more important metals and 
acids. 

For purposes of study and investigation the metals have 
been placed in groups or classes. The groups being arranged 
according to the action of certain reagents, which will pre¬ 
cipitate some of the metals from a solution and leave others. 

Where a partial solution has been made, the mixture is 
then filtered and by this means a further separation attained. 
The filtrate is then treated with some other reagent and a still 
further separation accomplished. These processes are re- 









37 


peated until an individual substance is obtained, the latter is 
then subjected to one or more special tests for its identification. 

It is evident from the above that the principles of solution 
and precipitation are of the utmost importance in qualitative 
analysis, and should be thoroughly mastered in order to attain 
good results in this work. 

Since a knowledge of the individual tests for each metal 
must first be acquired, a certain number of tests will be given, 
and its properties studied; then the metals of that group will 
be examined together. 

The first group is composed of metals whose chlorides are 
insoluble in water, as lead, silver and mercurous mercury. 

METALS 

Lead Group (First) Pb, Ag, Hg 1 

Solutions of lead salts give with: 

Soluble chlorides, a white heavy ppt. of PbCl 2 soluble in 
boiling water, insoluble in NH 4 OH. 

Hydrogen sulphide, a black ppt. of PbS, decomposed by 
hot cone. HNO s into PbS0 4 , also converted into PbS0 4 by 
heating with H 2 0 2 . 

Soluble sulphates, a heavy white ppt. of PbS0 4 insoluble 
in dilute acids. 

Soluble chromates, a bright yellow ppt. of PbCr0 4 insoluble 
in acetic acid, soluble in mineral acids. 

Solutions of silver salts give with: 

Soluble chlorides, a white curdy ppt. of AgCl, which 
blackens in the light. The ppt. is insoluble in water (hot or 
cold), soluble in NH 4 OH, forming (NH 3 ) 2 AgCl, which is re¬ 
precipitated on the addition of nitric acid dil. The ppt, is 
soluble in KCN solution. 
















. 













































































































38 


Hydrogen sulphide a black ppt. of Ag 2 S, insoluble in acids, 
soluble in KCN, sodium thiosulphate and nitric acid. 

Soluble iodides and bromides (not fluorides) give heavy 
curdy ppt. like the chloride; afifected by light, also soluble in 
KCN and sodium thiosulphate. 

Soluble chromates a reddish brown ppt. of Ag 2 Cr0 4 , solu¬ 
ble in strong acids. 

Caustic alkalis a yellowish gray ppt. of silver oxide. 

Solutions of mercurous salts give with: 

Soluble chlorides, a white heavy ppt. of HgCl, insoluble 
in acids; soluble in aqua regia giving HgCl 2 . Reacts with 
NH 4 OH, forming NH 2 HgCl and Hg which is black. Decom¬ 
posed by fixed alkalis into Hg 2 0, also black. 

Hydrogen sulphide gives a black ppt. of Hg 2 S, insoluble 
in acids, soluble in aqua regia. 

Caustic alkalis a black ppt. Hg 2 0, insoluble in excess. 

Dry salts, both of mercurous and mercuric mercury, heated 
with sodium carbonate in a test tube give a gray deposit of 
mercury (globules) in the cooler part of the tube. 

Lead Group Scheme. 

Solution containing soluble salts of lead, silver and mer¬ 
curous mercury. 

Add hydrochloric acid dil. in slight excess and filter. 

Ppt. A. Filtrate A reject. 

Treat with boiling water several times : Residue (a), solu¬ 
tion (a), Treat solution (a) with K 2 Cr 2 0 7 , a heavy yellow 
ppt. = PbCr0 4 . 

Residue (A). Treat with NH 4 OH several times. Residue 
(B). Solution ( b ). 

To solution ( b ) add HNO s dil., a white curdy ppt. =AgCl. 





39 


Residue (B), if black, due to NH 2 Hg 2 Cl = Hg(ous). 

The second group is made up of two parts. The tin group 
and the copper group. All these metals are precipitated by 
hydrogen sulphide in acid solution. The sulphides of the 
first part are soluble in strong ammonium sulphide, the sul¬ 
phides of the second part are insoluble in ammonium sulphide. 

Copper Group (Second), Hg, Bi, Cu, Cd. 

Solution of mercuric salts give with: 

Hydrogen sulphide, in excess, in acid solution, a black ppt. 
of HgS. Insoluble in acids and ammonium sulphide; soluble 
in aqua regia. 

Fixed alkalis, a yellowish-red ppt. of HgO, insoluble in 
excess. 

Ammonium hydroxide, a white ppt. of ammonio-mercuric 
chloride, NH 2 HgCl, insoluble in excess, but soluble in acids. 

Potassium iodide, a bright red ppt. of Hgl 2 , soluble in 
excess, forming (KI) 2 HgI 2 . 

Stannous chloride, SnCl 2 , gives a white ppt. at first, of 
HgCl, with excess a gray or black ppt. of Hg. 

Copper, a gray ppt. on the copper, which when heated in a 
glass tube gives a deposit of mercury globules in the cooler 
portion of the tube. 

Solutions of bismuth salts give with: 

Hydrogen sulphide, a black ppt. of Bi 2 S 3 , insoluble in 
dilute acids, soluble in hot HN0 3 . 

Fixed alkalis and ammonium hydroxide give a white floc- 
culent ppt. of Bi(OH) 3 , insoluble in excess, soluble in dilute 
acids. 

Soluble chromates, a yellow ppt. of basic bismuth chromate 
soluble in strong acids. 




• • 










% 









































. • 





































































40 


Water, a heavy white ppt. of a basic salt. The nitrate 
gives Bi0N0 3 , the chloride gives BiOCl, soluble in nitric or 
hydrochloric acid. 

Potassium stannite (K 2 Sn0 2 ),* a black ppt. of Bi. 

Salts heated on charcoal with bismuth flux (a mixture of 
KI and S) give a bright red incrustation. 

Solutions of copper Salts give with: 

Fixed alkali hydroxides, a blue ppt. of Cu(OH) 2 , insoluble 
in excess, soluble in certain organic acids and NH 4 OH. 

Ammonium hydroxide, at first a blue ppt., soluble in excess 
forming a complicated salt, having a deep blue color. 

Hydrogen sulphide in acid solution, a black ppt. of CuS 
insoluble in dilute acids except nitric acid (distinct from HgS), 
insoluble in boiling dilute H 2 S0 4 (distinct from CdS). 

Potassium cyanide, a brown ppt. of Cu(CN) 2 , soluble in 
excess forming a double cyanide. The latter solution is not 
precipitated by H 2 S (distinction from Cd). 

Potassium ferrocyanide [K 4 Fe(CN) 6 ] in acetic acid, a red 
brown ppt. of Cn 2 Fe(CN) 6 , which will form even in a very 
dilute solution. 

Copper salts heated on charcoal with tin and borax give a 
red bead due to Cu 2 0. 

Heated in the borax bead, oxidizing flame, give a green 
bead hot, and blue when cold. 

Solutions of cadmium salts give with: 

Fixed alkali hydroxides, a white ppt. of Cd(OH) 2 insoluble 
in excess. 

Ammonium hydroxide, a white ppt., soluble in excess (dis¬ 
tinct from Bi). 

* Made by adding KOH to SnCl* until the ppt. first formed is re¬ 
dissolved. 








41 


Hydrogen sulphide in aeid solution, a bright yellow ppt. 
of CdS, soluble in boiling dilute sulphuric acid, insoluble in 
potassium cyanide (distinctions from Cu). 

Heated on charcoal in the oxidizing flame gives a brown 
coat of the oxide. 

The borax bead is yellow when hot, colorless when cold. 

Copper Group Scheme. 

If the solution is not already acid make it slightly acid with 
HN0 3 dilute and pass in H 2 S gas in excess and filter. 

Ppt. A. Filter reject. 

Treat precipitate (A) with HNO s dilute, several times 
solution (A). 

Residue A = HgS: Dissolve in aqua regia, boil out Cl, 
and filter if necessary. Add SnCl 2 , a white ppt. becoming 
black on further addition of SnCl 2 = Hg. 

Solution (A). Boil out H 2 S filter if necessary add 
NH 4 OH in slight excess and filter. 

Ppt. B. Filtrate B. 

Dissolve ppt. B in a small amount of warm HCl cone, and 
pour into a large beaker of water, a heavy white ppt. = BiOCl. 
Or add to a part of the HC1 solution potassium stannite a black 
ppt. =: Bi. 

Filtrate B. If blue copper is probably present. Make a 
portion acid with acetic acid and add K 4 Fe(CN) 6 a red-brown 
ppt. = Cu 2 Fe(CN) 6 . 

If Cu is present, make remaining solution slightly acid 
with H 2 S0 4 dilute and pass in H 2 S in slight excess, boil, filter 
and pass H 2 S into filtrate; a bright yellow ppt. = CdS. 

Tin Group (Second), Sn 11 , Sn IV , As 111 , As v , Sb. 

Tin forms two classes of compounds stannous Sn 11 and 
stannic Sn iv . 















































































. 













































































































































42 


Soluble stannous compounds give with : 

Fixed alkalis, a white ppt. of stannous hydroxide Sn(OH) 2 . 
soluble in excess forming alkali stannites, as K 2 Sn0 2 . The 
alkali carbonates also give the same ppt. 

Hydrogen sulphide in slightly acid solution, a brown ppt. 
of SnS. Soluble in HC1 cone., also in (NH 4 ) 2 S 2 , forming 
(NH 4 ) 2 SnS s (the stannic form). 

Mercuric chloride, a heavy gray ppt. of HgCl and Hg. 

Metals like Fe, Zn, Al, a precipitate of metallic tin. 

Soluble stannic compounds give with: 

Fixed alkali hydroxides and carbonates, a heavy white 
ppt. of stannic acid. H 2 SnO s , soluble in excess of the fixed 
alkali hydroxides. 

Hydrogen sulphide in slightly acid solution, a yellow ppt. of 
SnS 2 , soluble in concentrated HC1, (NH 4 ) 2 S 2 and aqua regia. 

Cone, solutions of sodium sulphate or ammonium nitrate 
on boiling, a heavy white ppt. of metastannic acid, H 10 Sn 5 O 15 . 
The latter compound is also formed by action of strong HNCh 
on tin. 

Compounds heated on charcoal, oxidizing flame with 
Co(N 0 3 ) 2 give a blue green colored mass. 

Arsenic. 

Arsenic also forms two classes of compounds As 111 and 
As v . 

Arsenious acid (H 3 At0 3 ) in solution, acid with HC1 dilute 
gives with: 

Hydrogen sulphide, a yellow flocculent ppt. of As 2 S 3 , in¬ 
soluble in HC1 cone., soluble in (NH 4 ) 2 S 2 , in aqua regia and 
ammonium carbonate (distinction from Sb and Sn). 

Thiosulphates when boiled, a yellow ppt. of As 2 S 3 (distinc¬ 
tion from Sb and Sn). 


















4 


1 




4 























































































43 


Metallic copper on boiling, a gray ppt. on the copper, of 
arsenic. (Reinsch.) 

Marsh test, see under arsenic for both As 111 and As v . 

Soluble arsenic compounds give with: 

Hydrogen sulphide in acid solution, a ppt. of S and at the 
same time the As v is reduced to the As 111 form. 

Ammonium sulphide, a soluble salt of ammonium arsenic 
sulphide, (NH 4 ) 3 AsS 4 , which when treated with HC1 dilute 
gives a yellow ppt. of As 2 S 5 . 

Magnesia mixture* a white crystalline ppt. of NH 4 MgAs0 4 
(similar to that with P0 4 ions). 

Ammonium molybdate on heating, of ammonium arseni- 
molybdate (compare with H 3 P0 4 ). 

Fleitman’s Test. —Place some A1 turnings in a test tube, 
containing KOH solution and warm, when hydrogen is evolved 
add some As 2 0 3 or As compound cover the mouth of the test 
tube with a piece of filter paper moistened with AgN0 3 and 
allow to stand a few minutes. A black spot will appear on 
the paper. 

Compounds of As heated on charcoal give a white vapor of 
As 2 0 3 with an odor of garlic, the fumes are poisonous. 

Antimony. 

Solutions of antimony give with: 

Fixed alkali hydroxides, a white ppt. of Sb(OH) 3 soluble 
in excess. The same ppt. is produced by NH 4 OH but is in¬ 
soluble in excess. The ppt. is also soluble in tartaric acid. 

Hydrogen sulphide, an orange ppt. of Sb 2 S 3 , soluble in 
HC1 cone., and in (NH 4 ) 2 S 2 . 

Water in excess, a heavy white ppt. of the basic salt SbOCl, 
soluble in strong acids. 

* See footnote page 35. 










44 


Nascent hydrogen, hydrogen, antimonide H 3 Sb, see under 
Marsh test for arsenic. 

Fleitman’s test no reaction (distinction from arsenic). 

Antimony compounds heated on charcoal, in the oxidizing 
flame give a white coat of Sb 2 0 3 . If this is treated with a 
drop of (NH 4 ) 2 S it becomes orange colored due to Sb 2 S 3 . 

Heated in the reducing flame with Na 2 C0 3 antimony com¬ 
pounds give a brittle metallic mass of Sb. 

Gold. 

Solutions of gold are precipitated by hydrogen sulphide in 
acid solutions Au 2 S 3 . Insoluble in mineral acids, soluble in 
ammonium and alkali sulphides, also in equa regia. 

Potassium and sodium hydroxide give a brown ppt. of 
Au(OH) 3 , soluble in excess. 

Ammonium hydroxide give a brown ppt. of fulminating 
gold. 

Ferrous sulphate gives a brownish black ppt., or it may 
have a metallic luster, of gold. 

Oxalic acid, on heating the solution, gives a bright yellow 
ppt. of metallic gold, the form of the ppt. depending upon 
conditions. Chlorine or nitric acid should be absent from 
the solution. 

Sulphurous acid, and many other reducing agents, also 
precipitate gold from its solutions. 

To some SnCl 2 add a drop of HN0 3 and boil = SnCl 4 ; 
add more SnCl 2 and pour this mixture into AuC 1 3 ; a deep 
purple ppt. called the Purple of Cassius is formed. 

Platinum. 

Hydrogen sulphide in acid solution produces a black ppt. of 
platinic sulphide, PtS 2 . Insoluble in strong acids. Soluble in 
ammonium sulphide and in aqua regia. 














« 





I 











* 















































45 


Potassium and ammonium chloride give yellow crystalline 
ppts. of potassium and ammonium, platinic chloride respec¬ 
tively, K 2 PtCl 6 , (NH 4 ) 2 PtCl 6 ; both insoluble in 50 per cent 
ethyl alcohol. Decomposed by ignition into spongy platinum. 

Ferrous sulphate gives a ppt. of platinum, only after long 
boiling. 

Oxalic acid does not give a ppt. with solutions of platinum 
(distinction from gold). 

Stannous chloride reduces platinic to platinous compounds 
in strong hydrochloric acid solution. The solution becomes 
darker, due to the change. 

Compounds of platinum heated on charcoal yield the spongy 
metal. 

Tin Group Scheme. 

Boil a portion of the clear solution with FeS0 4 ; if a black 
ppt. is formed add FeS0 4 to the rest of the solution, boil and 
filter. 

Ppt. A. Filtrate A. 

Ppt. A. Dissolve in dil. aqua regia, boil out Cl and evap¬ 
orate to small bulk; Add a strong solution of NH 4 C1, a yellow¬ 
ish red ppt. == (NH 4 ) 2 PtCl 6 . Filter and test filtrate with 
FeS0 4 or oxalic acid, boil if the latter is used; a brown or 
yellow ppt., which on filtering, drying and burnishing, shows a 
yellow color = Au. 

Filtrate A. Pour into a Marsh apparatus, and pass gases 
into a solution of AgNCX for several minutes, then filter. 

Ppt. B. Filtrate B. 

Dissolve ppt. B. in aqua regia dilute, boil out Cl, filter and 
add H 2 S to filtrate; an orange red ppt. = Sb 2 S 3 . 

Filtrate B. Add HC1 dil. to ppt. Ag, filter until clear and 
add H 2 S, a yellow ppt. = As 2 S 3 . 

















46 


Mixture in the flask of the Marsh apparatus, boil until zinc 
is dissolved. Decant clear liquid, wash residue, once or twice, 
dissolve in HC1 cone., filter and test filtrate with HgCl 2 ; a 
white or gray ppt. = HgCl, or Hg, shows the presence of Sn. 

Iron Group (Third), Fe 11 , Fe m , Al. Or, Be. 

Solutions of ferrous salts give with: 

Alkali hydroxides, a white ppt. rapidly becoming dark, of 
ferrous hydroxide, which becomes brown on standing in the 
air, due to oxidation to the ferric form. 

Alkali carbonates, a white ppt. of ferrous carbonate, chang¬ 
ing by oxidation to a basic ferric salt. 

Hydrogen sulphide in alkaline solutions only a black ppt. 
of FeS, soluble in dilute mineral acids. 

Alkali sulphides give a similar reaction to H 2 S. 

Potassium ferrocyainde, a pale blue ppt. of potassium 
ferrous ferrocyanide, K 2 Fe n , Fe(CN) 6 . Changed by ex¬ 
posure to air to ferric ferrocyanide, Fe 4 [Fe(CN) 6 ] 3 Prussian 
blue. Not affected by acids, decomposed by alkalies. 

Potassium fericyanide, K 3 Fe(CN) 6 , a deep blue ppt. of 
ferrous ferricyanide, Fe 3 [Fe(CN) 6 ] 2 , distinction from ferric 
salts. 

Nitric acid, chlorine and other oxidizers, ferric salts. 

Borax bead in the reducing flame, a light green color. If 
held in the oxidizing flame the iron is oxidized and the bead 
becomes yellow while hot, colorless when cold. 

Non-magnetic compounds heated on charcoal in the reduc¬ 
ing flame, become magnetic due to the formation of Fe 3 0 4 . 

Solutions of ferric salts give with: 

Alkali hydroxides and also carbonates, a brown ppt. of 
ferric hydroxide, insoluble in excess. 




4 





















* 

, 


9 























































































47 


Hydrogen sulphide no ppt. but are reduced to the ferrous 
state. „ 

Alkali sulphide reduction of the salt to ferrous, a ppt. of 
ferrous sulphide FeS. 

Sodium acetate on boiling, a red brown ppt. of the basic 
acetate Fe(0H)^(C 2 H 3 0 2 )y. 

Potassium ferrocyanide, a dark blue ppt. of ferric ferro- 
cyanide, Fe 4 [Fe(CN) 6 ] 3 , Prussian blue. 

Potassium ferricyanide, not ppt. (distinction from ferrous). 

Soluble sulphocyanates, a deep red (blood red) color, dis¬ 
tinction from ferrous. 

Borax bead, oxidizing flame, yellow hot, colorless, cold. 

Aluminium. 

Solutions of aluminium salts give with: 

Fixed alkali hydroxide, a white gelatinous ppt. of Al(OH) 3 
soluble in excess (distinction from iron). 

Ammonium hydroxide, a similar ppt., insoluble in excess. 

Alkaline carbonates, a white gelatinous ppt. of Al(OH) 3 , 
insoluble in excess (distinction from Beryllium). 

Alkaline sulphides, also ppt. of the hydroxide. 

Alkali phosphates, a white ppt. of A1P0 4 , insoluble in 
acetic, soluble in mineral acids. 

Heated on charcoal the oxide remains white, but becomes 
blue when heated with Co(N0 3 ) 2 giving CoA1 2 0 4 . 

Chromium. 

Soluble chromium (Cr m ) salts give with: 

Alkali hydroxides, a green ppt. of Cr(OH) 3 soluble in 
excess of fixed alkali hydroxides, insoluble in NH 4 OH. The 
fixed alkali solution is ppted. by boiling, distinction from Al. 

Hydrogen sulphide, no ppt. Acid compounds, as chro- 









48 


mates, are reduced to the basic form; the yellow color of the 
former changes to the blue green color of the latter. 

Alkaline sulphides, similar reactions to aluminum. 

Oxidizing agents by boiling or fusion the acid form, shown 
by change of color from blue green to yellow. The chromic 
acid compounds as potassium chromate, give yellow ppts. with 
soluble barium or lead salts in acetic acid solution. 

Beryllium (Glucinum). 

The compounds of this metal are similar both to aluminum 
and also to magnesium, in analysis, the metal is separated with 
the iron group. 

Soluble compounds of beryllium give with: 

Fixed alkali hydroxides, a white gelatinous ppt., Be(OH) 2 , 
soluble in excess, also soluble in ammonium carbonate distinc¬ 
tion from the third group metals. 

Ammonium hydroxide, a similar ppt. 

Ammonium sulphide, a white gelationous ppt. of Be(OH ) 2 
similar to Al, distinction from Mg. 

Heat on charcoal and Co(N0 3 ) 2 , a gray mass, distinction 
from aluminum. 

Iron Group Scheme. 

Test a small portion for: 

Ferrous iron with K 3 Fe(CN) 6 , a blue ppt = Fe". 

Ferric iron with NH 4 SCN, a blood red color = Fe m . 

If ferrous iron is present, add 2 or 3 drops (not more) of 
HN0 3 cone., boil and add NH 4 C1 and NH 4 OH in slight excess 
heat to boiling and filter. 

Ppt. A. Filtrate, reject. 

Digest in the cold with ammonium carbonate, filter. 

Residue A. Solution A. 




















49 


Heat solution A to boiling, a white gelatinous ppt. = 
Be(OH) 2 . 

Residue A, mix with some water, add Na 2 0 2 , boil and filter. 

Residue B=:Fe(OH) 3 . 

Solution B. Divide into two parts. 

(1) Add NH 4 C1 and boil, a white gelatinous ppt. = 

Al(OH) g . 

( 2 ) Add acetic acid and lead acetate, a heavy yellow ppt. 
=* PbCr0 4 = Cr. 

Zinc Group (Fourth), Zn, Mn, Co, Ni. 

Solutions of zinc salts give with: 

Fixed alkali hydroxides, a white ppt. of Zn(OH) 2 soluble 
in excess, forming K 2 Zn0 2 , potassium zincite, distinction from 
Mn, Ni, Co; also from copper. 

Ammonium hydroxide, a similar ppt. soluble in excess. 

Alkali carbonates, a white ppt. of basic carbonate, soluble 
in alkali hydroxides and in ammonium carbonate. 

Hydrogen sulphide, an incomplete precipitation of the sul¬ 
phide ZnS in neutral solutions (mineral acids set free) but 
completely from the acetate or in acetic acid solution, distinc¬ 
tion from Mn, Ni, Co. 

Ammonium sulphide, a white flocculent ppt. ZnS. 

Sodium phosphate, a white ppt. of ZnHP0 4 , soluble in 
alkali hydroxides and most acids. 

Salts heated on charcoal with sodium carbonate give a white 
coating, which on the addition of Co(N0 3 ) 2 and heated again 
give a green-colored mass. 

Compounds heated in the borax bead are colorless, or con¬ 
centrated, yellow hot, white when cold. 



















50 


Manganese. 

Soluble manganese salts (Mn 11 ), give with: 

Fixed alkali hydroxides, a white ppt. of Mn(OH) 2 , in¬ 
soluble in excess, which on exposure to air becomes brown, due 
to the formation of a basic manganic compound. 

Ammonium hydroxide, an incomplete precipitation of the 
hydroxide; no ppt. is formed in the presence of NH 4 C1. 

Alkali carbonates, a white ppt. of the carbonate, which 
oxidizes in the air, and becomes brown. 

Hydrogen sulphide, no ppt. (except the acetate and this 
partially) not even in acetic acid solution, distinction from Zn. 

Ammonium sulphide, a pink ppt. of MnS, soluble in dilute 
acids, distinction from Ni and Co. 

Manganous salts (Mn 11 ) preferably the sulphate heated 
with a large volume of HNO s dilute and then some red lead 
Pb 3 0 4 or Pb0 2 added; after settling, show a deep purple color 
due to the formation of permanganic acid, HMn0 4 . 

Dry salts heated on charcoal with Na 2 C0 3 and some 
NaNO s , or better, fused in a nickel capsule give a green mass 
of sodium manganate (Mn VI ). 

This test may also be carried out in the loop of a platinum 
wire; a bright green non transparent bead is formed. 

Borax or microcosmic salt bead in the oxidizing flame, a 
violet color hot, amethyst color cold, due to manganic oxide. 
This bead heated in the reducing flame for some time finally 
becomes colorless from the reduction of the Mn 2 0 3 to the 
colorless MnO. 

The reduction of the above salt requires skill with the 
blowpipe and gives good practice for the continuous operation 
of the reducing flame. 































* 










c 










































































c 








































































% 

























51 


Cobalt. 

Soluble salts of cobalt give with: 

Fixed alkali hydroxides, a blue ppt. of basic salt. If 
boiled at once, a reddish ppt. of Co(OH) 2 insoluble in excess. 

Ammonium hydroxide, also an incomplete precipitation 
soluble in excess. 

Hydrogen sulphide in alkaline solution, or ammonium 
sulphide, a black ppt. of CoS, insoluble in excess, somewhat 
or slowly soluble in strong acids, soluble in aqua regia. 

Alkali carbonates, a basic salt somewhat soluble, in excess. 

Alkali cyanides, a brown ppt. of Co(CN) 2 , soluble in excess, 
forming a double salt Co(CN) 2 , 2 KCN; this treated with a 
few drops of HC1 and then heated changes the double salt into 
potassium cobalticyanide, K 3 Co(CN) 6 , distinction from Ni, as 
not reprecipitated by acids as with double cyanide of nickel. 

Nitroso-/?-napthol in acetic acid solution, a dull red ppt., 
distinction from Ni. 

Borax bead in the oxidizing flame, a blue color, hot or cold. 

Heated on charcoal with the reducing flame, a para¬ 
magnetic mass. 

Nickel. 

Soluble salts of nickel give with: 

Fixed alkali hydroxides, a light green ppt. of Ni(OH) 2 , 
insoluble in excess, soluble in NH 4 OH. 

Hydrogen sulphide in alkaline solution a black ppt of NiS, 
insoluble in acetic and dilute mineral acids, soluble in aqua 
regia. 

Alkali sulphides NiS, slightly soluble in strong (NH 4 ) 2 S. 

Potassium cyanide, a yellow green ppt. of Ni(CN) 2 , soluble 
in excess, forming the double cyanide. 





















52 


This solution heated with bromine water or sodium hypo¬ 
chlorite gives a ppt of nickelic hydroxide Ni 2 (OH) 6 (distinc¬ 
tion from Co). 

Borax bead in the oxidizing flame, a purple color hot, 
brown when cold. 

Compounds heated on charcoal in the reducing flame give 
a dark, slightly para-magnetic mass. 

Zinc Group Scheme. 

Add HN 4 C1, HN 4 OH, and (NH 4 ) 2 S in slight excess; or 
better than (NH 4 ) 2 S pass in H 2 S gas and filter: 

Ppt. Filtrate reject. 

Treat ppt. with HC1 dilute: 

Residue A. Solution A. 

Residue A, test with borax bead, blue = Co. Brown = Ni. 

If blue, dissolve residue in aqua regia, boil out Cl, and 
treat with a hot solution of nitroso-/Tnapthol until all Co is 
precipitated. Filter, pass H 2 S into filtrate, or add (NH 4 ) 2 S; 
a black ppt. ==NiS, confirm with borax bead. 

Solution A. 

Boil out H 2 S, add strong solution of NaOH filter. 

Ppt. B. Filtrate B. 

Dissolve ppt. B in warm H 2 S0 4 dilute add HNO s cone. 
I c.c. and HNO s dilute, io c.c. heat to boiling and add a small 
portion of pure Pb 3 0 4 , allow the mixture to settle, a deep 
purple colored solutionsHMn0 4 . 

Filtrate B, make slightly acid with acetic acid and add H 2 S, 
a white flocculent ppt. = ZnS. Test ppt. on charcoal. 

Calcium Group (Fifth), Ba, Cr, Ca and Mg. 

Precipitated as carbonates in alkaline solution; by ammo¬ 
nium carbonate, with ammonium chloride present; the mag¬ 
nesium redissolves and goes into solution. 









































































53 


Barium. 

Solutions of barium compounds give with: 

Alkali carbonates, a white flocculent ppt. of BaCO s , in¬ 
soluble in excess. 

Soluble sulphates, a heavy white ppt. of BaS0 4 , insoluble 
in all acids. 

Soluble phosphates, a white flocculent ppt. of BaHP0 4 , 
soluble in dilute acids. 

Soluble oxalates, a white crystalline ppt. of BaC 2 0 4 , solu¬ 
ble in mineral acids, insoluble in acetic acid. 

Soluble chromates or dichromates, a yellow ppt. of BaCr0 4 , 
soluble in HC1 or HNO s dilute, insoluble in acetic acid. 

Volatile compounds give a yellow green flame. 

Strontium. 

Solutions of stronitum compounds give with: 

Alkali carbonates, a white flocculent ppt. of SrCO ?i , insolu¬ 
ble in excess. 

Soluble sulphates, a heavy white ppt. SrS0 4 , insoluble in 
acids but more soluble than BaS0 4 , 

Soluble phosphates, also oxalates, similar ppts. to barium. 

Potassium chromate a yellow ppt. of SrCr0 4 , soluble in 
acids, including acetic. Potassium dichromate no ppt. 

Volatile compounds give a red flame (see lithium). 

Calcium. 

Solutions of calcium compounds give with: 

Alkali carbonates, a white flocculent ppt. of CaCCX, insolu¬ 
ble in excess, soluble in acids. Soluble in carbonic acid, form¬ 
ing Ca(HCO s ) 2 . On boiling the later gives CaCO s . 

Fixed caustic alkalies, in concentrated solutions, a white 
flucculent ppt. of Ca(OH) 2 ; ammonium hydroxide no ppt. 
















54 


Soluble sulphates in strong solutions, a heavy white ppt. of 
CaS0 4 , slightly soluble in cold, less in hot water. 

Soluble phosphates, a white flocculent ppt. of CaHP0 4 , 
soluble in acetic and mineral acids. 

Soluble oxalates, a white crystalline ppt. of CaC 2 0 4 , in¬ 
soluble in acetic acid, soluble in mineral acids. 

Soluble chromates, no ppt. 

Volatile compounds, a yellow red flame. 

Magnesium. 

Solutions of magnesium commpounds give with: 

Fixed alkali carbonates, a white flocculent ppt. of a basic 
salt, MgC0 3 , Mg(OH) 2 . 

Potassium and sodium hydroxides, a white ppt. of Mg(OH) 2 
insoluble in excess. 

Either ammonium hydroxide, or ammonium carbonate, 
only a slight precipitate. 

Barium hydroxide, in the absence of ammonium chloride, 
a white ppt. of Mg. (OH) 2 . 

Disodium hydrogen phosphate, in the presence of ammo¬ 
nium hydroxide, a white crystalline ppt of NH 4 MgP0 4 , in¬ 
soluble in NH 4 OH, soluble in dilute acids. 

Oxalates no ppt. (distinction from calcium). 

The compounds give no flame test. 

Calcium Group Scheme. 

Make the solution slightly alkaline with NH 4 OH, add 
NH 4 C1 until clear (to dissolve the Mg salt) and (NH 4 ) 2 C0 3 
in slight excess; filter and wash ppt. 

Filtrate A. 

Ppt. A. Dissolve in warm acetic acid and test a c.c. with 
K 2 Cr 2 0 7 solution; a yellow ppt. = Ba€r0 4 . If Ba is present, 














55 


add K 2 Cr 2 0 7 to the rest of the solution in slight excess and 
filter: 

Ppt. B, reject. Filtrate B. 

Filtrate B, make slightly alkaline with NH 4 OH and add 
(NH 4 ) 2 C0 3 in excess, filter and wash ppt. 

Filtrate C, reject. 

Ppt. C. Dissolve in a small quantity of warm acetic acid. 
Test a portion with CaS0 4 solution, a white ppt. coming down 
slowly — SrS0 4 . If Sr is present, add (NH 4 ) 2 S0 4 in excess 
to remainder of the solution, filter and add (NH 4 ) 2 C 2 0 4 to 
the filtrate, white cryst, ppt. = CaC 2 0 4 ; make flame test. 
Filtrate A. 

Add (NH 4 ) 2 S0 4 and (NH 4 ) 2 C 2 0 4 to remove traces of 
Ba, Ca, etc., filter and test filtrate with Na 2 HP0 4 , a white 
cryst. ppt. = NH 4 MgP0 4 . 

Sodium Group (Six), K, Na, Li, NH 4 . 

Potassium. 

Solutions of potassium compounds give with: 

Hydrogen platinic chloride, a yellow crystalline ppt. 
K 2 PtCl 6 , somewhat soluble in water, insoluble in strong 
alcohol. 

Tartaric acid in concentrated solution, a white crystalline 
ppt. of potassium hydrogen tartrate, KHC 4 H 4 O e , somewhat 
soluble in water, insoluble in alcohol. 

The salts heated in the clear flame impart a violet color. 
In the presence of sodium the color is usually obscured by the 
yellow; a piece of blue glass will absorb the yellow, but allow 
the violet to be observed. 







56 


Sodium. 

Nearly all compounds of sodium are soluble in water, so 
precipitation tests are of little value. 

The salts (especially the chloride) heated give an intense 
yellow flame which may be observed in the presence of most 
other flame coloring substances. 

Lithium. 

Only a few of the salts of this metal can be precipitated. 
The phosphate is probably the most important. 

Disodium hydrogen phosphate gives a white crystalline ppt. 
of Li 3 P0 4 . Filter, and moisten the ppt. with HC1 dilute and 
make flame test. A carmine flame. 

Ammonium. 

Solutions of ammonium compounds give with: 

Hydrogen paltinic chloride, a yellow crystalline ppt of 
(NH 4 ) 2 PtCl,., similar to the potassium compound. Both ppts. 
(K and NH 4 ), on ignition, leave a residue of spongy platinum. 
Tartaric acid, a similar ppt. to that of potassium. 
Ammonium salts heated with a solution of potassium, 
sodium or calcium hydroxide, give ammonia gas, which changes 
wet red litmus paper to blue. 

Nessler’s reagent, a yellow color or ppt., which is a very 
delicate test (see ammonium). 

Sodium Group Scheme. 

Make flame test for sodium. Test a portion of the solu¬ 
tion for NH 4 by heating with NaOH or KOH solution. Test 
fumes with wet red litmus paper. 

If NH 4 is present, evaporate the remainder of the solution 



57 


to dryness, ignite to remove NH 4 salt; take up residue with a 
small quantity of distilled water. Add Na 2 HP0 4 in slight ex¬ 
cess ; a white crystalline ppt. — Li 3 P0 4 ; moisten ppt. with 
HC1 cone, and make flame test tor Li, crimson flame. 

Test filtrate with H 2 PtCl 6 for K, a yellow crystalline ppt. 
= K 2 PtCl 6 , or make flame test using blue glass. 

General outline for the separation of the groups of metals. 
Absence of phosphates, silicates, oxalates and insoluble 
sulphates. 

Scheme Headings for all Groups. 

Tests on the Original Solution. 

Sodium, flame test, yellow. 

Ammonium, boiling with NaOH solution and testing for 
with wet red litmus paper. 

Ferrous iron, addition of potassium ferricyanide gives a 
blue ppt. 

Ferric iron, addition of ammonium thiocyanate gives a 
blood red color. 

Stannic tin, addition of ammonium nitrate or sodium sul¬ 
phate and boiling gives a white ppt., which heated on charcoal 
with Co(N 0 3 ) 2 gives a green mass = Sn. 

Arsenic, (As v ), add magnesia mixture, filter white ppt. 
and dissolve it in HC1 dilute. Add Na 2 S0 3 , boil and pass in 
H 2 S gas; a yellow ppt. = As 2 S 3 = As(ic). 

Separations. 

To the clear solution, add HC1 dilute in excess; a white 
ppt. = first group, filter and treat ppt. according to first group 
scheme. 










58 


Pass H 2 S gas into the filtrate; ppt. may be. black, brown, 
yellow, etc. = second group, copper and tin group subdivisions. 

Filter; Ppt., A. Filtrate A. 

Treat ppt. A with strong (NH 4 ) 2 S 2 -to dissolve the tin 
group. 

Residue B, examine according to scheme for the Cu group. 

Solution B, add HC1 dilute, filter off ppt. and treat accord¬ 
ing to scheme for Sn group. 

Filtrate A, boil out H 2 S, filter if necessary and if Fe has 
been found, add one or two drops of HNO s cone, and boil; 
then apply scheme for third group. 

Filter off third group and examine filtrate for fourth group. 
Add (NH 4 ) 2 S in slight excess, filter. Ppt. C. Filtrate C. 

Test ppt. C for fourth group according to scheme. 

Filtrate C, boil out (NH 4 ) 2 S, filter if necessary, and apply 
method for fifth group. 

After precipitating with (NH 4 ) 2 C0 3 , filter. 

Ppt. D. Filtrate D. 

Test ppt. D according to scheme for fifth group. 

Test filtrate D for Mg as in scheme. 

ACIDS 

Acids, for convenience, are divided into groups, in the 
same way as the metals, but at the most this method is very 
incomplete and not nearly so satisfactory as for the metals. 

In practice acids are often tested for directly, where only 
a few are present, using characteristic tests for that purpose. 
If the acids occur as insoluble compounds (like BaS0 4 , etc.), 
they must be brought into solution before their characteristic 
tests can be applied. 





























































59 


First Group. 

The acids of this group are precipitated by barium chloride, 
Sulphuric, sulphurous, thiosulphuric, phosphoric (ortho) 
boric, hydrofluoric, silicic, carbonic, chromic, arsenious, 
arsenic, oxalic, tartaric, citric. 

A few reactions for each will be given. 

Sulphuric Acid. 

Soluble sulphates give with: 

BaCl 2 a heavy white ppt. of BaS0 4 , insoluble in strong 
acid. 

Lead acetate, a heavy white ppt. of PbS0 4 , insoluble in 
dilute acids. 

Sulphates (ex. CaS0 4 ) with a strong solution of calcium 
chloride, a heavy white ppt. of CaS0 4 , slightly soluble in cold, 
almost insoluble in hot water. 

Sulphate heated on charcoal with Na 2 C0 3 yield Na 2 S. 
This salt placed on a silver coin and moistened with water 
gives a black stain of Ag 2 S. 

Sulphurous Acid. 

Soluble sulphites give with: 

Barium chloride, a white ppt. of BaSO s , soluble in HC1 
dilute; solution heated with HN0 3 cone, a heavy white ppt. 
of BaS0 4 , insoluble in acids. 

Lead acetate, a white ppt. of PbS0 3 , soluble in HNO s 
dilute. 

Silver nitrate, a white ppt. of Ag 2 S0 3 (soluble in HNO s 
dilute, which on boiling gives Ag. 

HC1 dilute S0 2 gas recognized by its odor; no ppt. of S is 
formed, distinction from thiosulphates. 



■* 






60 


Carbonic Acid. 

A solution of C0 2 in water (H 2 C0 3 ) or C0 2 gas gives 
with: 

Calcium hydroxide, a white ppt. of CaC0 3 , soluble in excess 
of the acid (gas) forming Ca(HCO s ) 2 . This compound is 
not very stable, decomposed by boiling into CaC0 3 , C0 2 , H 2 0. 
Soluble carbonates give with: 

Barium chloride, a white ppt. of BaCO s soluble in dilute 
acids. 

Silver nitrate, a white ppt. of Ag 2 C0 3 . 

Calcium chloride, a white ppt. of CaCO s . 

Carbonates (ex. Na + K) when heated are decomposed 
into C0 2 and the oxide of the metal. 

Silicic Acid. 

Colloidal solutions of silicic acid have been prepared and 
these when evaporated yield the anhydride, Si0 2 ; a white 
powder insoluble in water and acids except HF. 

Soluble silicates give with: 

Barium chloride, a white gelatinous ppt. of BaSi0 3 . 
Calcium chloride, a white gelatinous ppt. of CaSi0 3 . 

HCl and other strong acids, a white gelatinous ppt. of 
H 2 Si0 3 . 

Silicates heated in the sodium ammonium phosphate bead, 
give a cloudy bead hot, clear when cold. 

Hydrofluoric Acid. 

It etches glass (see fluorine), forming first SiF 4 , then 
H 2 SiF 6 . 

Soluble fluorides give with: 









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61 


Barium chloride, a white ppt. of BaF 2 soluble in HNO a or 
HC1, decomposed by H 2 S0 4 into BaS0 4 and HF. 

Calcium chloride gives a similar reaction^ 

Ortho Boric Acid H 3 B0 3 . 

Soluble borates give with: 

Barium chloride or calcium chloride, a white ppt. of meta 
borate, Ba(B0 2 ) 2 Ca(B0 2 ) 2 , respectively. 

Boric acid, or borates mixed with H 2 S0 4 cone, added to 
alcohol and the alcohol ignited, impart a green color to the 
flame. 

A solution of boric acid changes the yellow color of turmeric 
paper to red or red brown, better after drying. 

Ortho Phosphoric Acid. 

Soluble orthophosphates give with : 

Barium chloride, a white ppt. of BaH(P0 4 ), soluble in 
dilute HC1, HN0 3 and acetic acid. 

Calcium chloride also gives a similar ppt. CaHP0 4 , soluble 
in acetic acid, distinction from calcium oxalate. 

With ammonium molybdate a yellow crystalline ppt. form¬ 
ing easily in the cold; distinction from arsenic and silicic acids. 
The ppt. is insoluble in HN0 3 , soluble in NH 4 OH. 

Magnesia mixture; white crystalline ppt. of NH 4 MgP0 4 . 
Distinction between orth, meta and pyro (see phosphorus). 

Chromic Acid. 

Soluble chromates give with: 

Barium chloride, a yellow ppt. of BaCr0 4 , soluble in strong 
acids, insoluble in acetic acid. 

Calcium salts no ppt. unless very concentrated, distinction 
between Ba and Ca. 










62 


Silver nitrate, a reddish ppt. of Ag 2 Cr0 4 , soluble in nitric 
acid and fixed alkali hydroxides. 

Lead acetate, a yellow ppt. of PbCr0 4 , soluble in nitric 
acid, insoluble in acetic acid. 

Hydrogen sulphide, and some other reducing agents, in 
sulphuric acid solution, a change in color from yellow (acid 
form of chromium) to blue green (basic form of chromium). 

H 2 0 2 , a change of color, yellow to blue; the latter due to 
perchromic acid H 2 Cr 2 O s (see hydrogen dioxide). 

Second Group. 

Precipitated by AgNO s in HN0 3 dilute solution.- HC1, 
HBr, HI, HCN, HSCN, H 2 S, HN0 2 , for others see reference 
books. 

Hydrochloric Acid. 

Soluble chlorides give with: 

Silver nitrate, a white curdy ppt. of AgCl, insoluble in 
HNO s dilute, soluble in NH 4 OH, KCN and Na 2 S 2 0 3 . 

Lead acetate, a white crystalline ppt. of PbCl 2 , soluble in 
boiling water. 

Chlorides heated with Mn0 2 and H 2 S0 4 the yellow green 
gas chlorine; distinction from iodine, bromine and fluorine. 

Chlorides mixed with K 2 Cr 2 0 7 and H 2 S0 4 cone, yield when 
heated, the red gas chromyl chloride Cr0 2 Cl 2 . If this gas is 
passed into water, on the addition of barium acetate, a yellow 
ppt., BaCr0 4 , will be formed. I and Br give no volatile Cr 
compounds. 

Hydrobromic Acid. 

Soluble bromides give with : 

Silver nitrate, a yellow white ppt. of AgBr, less soluble in 



























63 


NH 4 OH than the chloride, soluble in KCN, etc., insoluble in 
HNO s dilute. 

Lead acetate, a white crystalline ppt. of PbBr 2 , soluble in 
boiling water. 

Bromides mixed with Mn0 2 and strong H 2 S0 4 yield a red 
brown gas, Br, distinction from Cl and I. 

Chlorine gas acting on a bromide sets Br free (see bromine). 

Hydriodic Acid. 

Soluble iodides give with : 

Silver nitrate, a yellow white ppt. of Agl almost insoluble 
in NH 4 OH, soluble in KCN, etc. 

The chloride, bromide and iodide of silver are reduced by 
the action of light and become first bluish, then black. 

Lead acetate, a yellow crystalline ppt. of Pbl 2 , soluble in 
boiling water. v 

Iodides mixed with Mn0 2 and strong H 2 S0 4 yield a violet 
colored vapor = I, distinction from Cl and Br; the vapor also 
when cooled becomes solid. 

Chlorine gas acting upon an iodide sets I free (see iodine). 
Hydrocyanic Acid. 

Soluble cyanides give with: 

Silver nitrate, a white ppt. of AgCN, soluble in KCN. 

Cyanides heated with sulphuric acid give an effervescence 
and the odor of peach blossoms.* 

A few drops of (NH 4 ) 2 S and heated sulphocyanide, this 
made acid with HC1 dilute and FeCl 3 added gives a blood red 
color (see ferric iron test). 

* Use great care when smelling the gas, as it is one of the most 
poisonous substances known. 











































64 


NaOH, FeS0 4 , FeCl 3 and after heating made acid with 
HC1 dilute a blue ppt. 

Thiocyanic Acid. , 

Soluble thiocyanates give with. 

Silver nitrate, a white ppt. of AgSCN, soluble in NH 4 OH. 
Ferric chloride, a deep red color, which disappears on the 
addition of mercuric chloride. 

Nitrous Acid. 

Soluble nitrites give with: 

Silver nitrate, a white ppt. of AgN0 2 somewhat soluble in 
water. 

Acetic acid and starch paste iodide mixture, a blue color. 

Oxalic Acid. 

Soluble oxalates give with: 

Barium chloride, a heavy white ppt. of BaC 2 0 4 , soluble in 
mineral acids, insoluble in acetic acid. 

Calcium chloride, a white crystalline ppt. of Ca 2 C 2 0 4 , 
soluble in HQ or HN0 3 , insoluble in acetic acid, distinction 
from phosphate. 

Oxalates heated with H 2 S0 4 cone, are decomposed and give 
CO and C0 2 gases. 

If calcium (or other) oxalate, which gives no reaction with 
acetic acid, is igniteid, it changes to carbonate; then on the ad- 
ditio of acetic acid it effervesces. 

Tartaric Acid. 

Soluble tartrates give with : 

Barium chloride, a white ppt. of BaC 4 H 4 O e , soluble in 
acids. 









65 


Calcium chloride, a white ppt of CaC 4 H 4 O e , soluble in acids 
and fixed cuastic alkalis in the cold, distinction from cirtic acid. 

Silver nitrate, a white ppt. of Ag 2 C 4 H 4 O e , soluble in 
NH 4 OH, and on boiling the solution a ppt of Ag is formed, 
distinction from citrates. 

Tartrates ignited with H 2 S0 4 cone., give an odor like burnt 
sugar, distinction from citrates, also a black residue. 

Calcium hydroxide, a white ppt. of CaC 4 H 4 0 6 , distinction 
from citrates. 

Citric Acid. 

Soluble citrates give with: 

Barium chloride in strong solution, a white ppt. of barium 
citrate. 

Calcium chloride, a white ppt. of calcium citrate, insoluble 
in sodium or potassium hydroxide, distinction from tartrate. 

Calcium hydroxide solution in the cold, no ppt., distinction 
from tartrates. 

Silver nitrate, a white ppt. of silver citrate, not reduced by 
boiling, distinction from tartrates. 

Citrates heated with H 2 S0 4 cone., a carbonaceous residue 
but no odor of burnt sugar (see tartrates). 

Third Group. 

The acids of this group are not precipitated by barium 
chloride or by silver nitrate. 

Nitric Acid. 

All nitrates, except basic nitrates, are soluble in water. 

See test for nitrates under nitric acid. 

Nitrates treated with H 2 S0 4 dilute and starch paste iodide 
mixture give no blue color, distinction from nitrites. 










66 


Chloric Acid. 

All chlorates are soluble in water. 

Chlorates warmed (use care) with H 2 S0 4 cone, yield a 
yellow green gas, chlorine dioxide C10 2 ; its odor differs from 
that of chlorine. 

Chlorate solutions give no ppt. with AgN0 3 solution. If 
a chlorate is ignited, the residue dissolved in water, and AgND 3 
then added a white ppt. will be former of AgCl, insoluble in 
HNO s dilute, distinction from nitrate, which gives no ppt. 
after ignition, with AgNO s and HNO s dil. 

Acetic Acid. 

Acetates give with: 

Strong H 2 S0 4 and ethyl alcohol, when heated, a character¬ 
istic odor due to ethyl acetate C 2 H 5 C 2 H 3 0 2 . 

Salicylic Acid, HC 7 H 5 0 3 . 

Salicylates give with H 2 S0 4 cone, and methyl alcohol, when 
heated the characteristic odor of oil of wintergreen due to 
methyl salicylate CH 3 C 7 H 5 0 3 . 

Separations. 

To the clear solution (or salts of the* acids) add Na 2 C0 3 
solution in slight excess, boil and filter, 
ppt. 

Bases as carbonates or hydroxides reject. 

Filtrate. Sodium salts of the acids. 

First group. 

Make a small portion neutral with HC1 dilute and test 
with BaCl 2 for the first group. If present look for the follow¬ 
ing acids only: H 2 S0 4 , H 3 P0 4 , H 2 C0 3 , H 2 C 2 0 4 . 

Add HC1 to original, if effervescence, test gas. 

























































• 











♦ 

























67 


Odorless = C0 2 . 

Odor like a had egg, or gas blackens lead paper =H 2 S. 

Odor of bitter almonds = HCN. 

Odor of burning sulphur, with no ppt. of S = H 2 S0 3 . 

Odor of burning sulphur, white ppt. of S = H 2 S 2 0 3 . 

To neutral solution add BaCl 2 in slight excess filter: 

Treat ppt. with HN0 3 dilute, a white residue = BaS0 4 . 

Solution: add to portions : 

(1) NH 4 OH until slightly alkaline, then make acid with 
acetic acid, a white residue = BaC 2 0 4 ; ignite in a porcelain 
dish, cool and add HC1 dil., effervescence = oxalates. 

( 2 ) Add (NH 4 ) 2 Mo 0 4 , a yellow crystalline ppt. = H 3 P0 4 . 

If solution after boiling with Na 2 C0 3 was colorless, chromic 

acid is absent. If yellow, make a portion neutral with acetic 
acid, add CaCl 2 and filter. To filtrate, add BaCl 2 , a yellow 
ppt. = BaCr0 4 . 

Filtrate from Na 2 C0 3 ppt.: 

Second group. 

Make a portion nearly neutral with HNO s dil. and add 
AgN0 3 , a white curdy ppt. = second group acids. 

If present, make another portion of the solution acid with 
HC1 dil. and Test: 

( 1 ) A portion for HSCN with FeCl 3 , blood red color. 

( 2 ) A portion for I and Br with Cl water and CS 2 (see 
under bromine and iodine). 

If Br and I are absent, a white curdy ppt. with AgNO s = 
AgCl or AgCN (unless CN was absent), the latter is also 
decomposed by HC1 cone., AgCl is not. 

Tests for other acids as HN0 3 , HC10 3 , HC 2 H 3 0 2 . 

To test for nitrates and chlorates. If second group acids 
are present add Ag 2 S0 4 in slight excess, filter, and add to 









68 


filtrate, Na 2 C0 3 , filter, evaporate filtrate and ignite. After 
taking up with water, add AgN0 3 and HNO s dil., a white 
ppt. of AgCl — C10 3 . 

If chlorates are present they should be removed by evap¬ 
orating some of the sodium carbonate solution to dryness, and 
igniting carefully to drive off the oxygen from the chlorate, 
but not to decompose the nitrate. Take up residue with water 
and test for NO s (see Nitric Acid). 

Acetic Acid. 

Make a portion of the sodium carbonate solution slightly 
acid with H 2 S0 4 dil.; add H 2 S0 4 cone, ethyl alcohol and boil, 
the odor of ethyl acetate = acetic acid. 






























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